Magneto



Oct. 10, 1939,` F. G. HOBAT 2,175,664

l HUI' I Filed Aug. 26, 19157 ZNVENTOE HT TOEN/EY Patented Oct. 10, 1939` UNITED y STATES PATENT OFFICE MAGNET'O Franklin G. Hobart, Beloit, Wis., assigner to Fairbanks, Morse & Oo., Chicago, Ill., a corporation of Illinois An object of the present invention is to provide an improved ignition system for gas or gasoline engines which are too large to be started by hand cranking methods and yet which are not large enough to warrant the use of cranking means of compressed air, electrical or other relatively expensive type.

Another object is to provide simple, inexpensive means for application to a magneto of conventional construction, whereby such magneto may be operated manually Vto produce a spark for engine starting,I or other purposes.

Yet another object is to provide a simplified and improved dual magneto ignition system for gas or gasoline engines, wherein one of the magnetos, used for starting purposes, has switching means embodied therein for selectively circuiting the magnetos with the engine.

Other objects and advantages will appear from the following description, and from the drawing in which:

Fig. 1 illustrates somewhat diagrammatically, the operative. relation of the magneto ignition system to an internal combustion engine; Fig. 2 is a side elevation of the starting magneto assembly, with portions thereon in section; Fig. 3 is an end View of the starting magneto; Fig. 4 is a fragmentary plan view of a portion of the starting magneto assembly; Fig. 5 is a fragmentary sectional view of the starting magneto actuating mechanism; showing a modified form of the circuit control switch, and Fig. 6 is an end elevation of Fig. 5.

Generally described, my improved ignition system utilizes a starting magneto or hand sparker i!) and a running magneto I I which is operatively coupled to a suitable rotating part of an engine 52. The starting magneto I embodies a springdriven actuator, sometimes referred to as an impulse coupling. This mechanism is powered by a spring which is adapted to be successively loaded and released to impart intermittent, highly accelerated rotational impulses to the rotor of the starting magneto, whereby to produce a high voltage E. M. F. at the terminals of the magneto. Impulse couplings of this character are well known and have heretofore been employed in connection with magnetos for the described purpose. An impulse coupling of the type suitable for use in the present invention is described and illustrated in United States Letters Patent No. 1,189,326 of July 4, 1916. Inasmuch as the particular construction of such devices is not of the essence of the present invention,y the same will not be'described in detail.

.plug i3 by a conductor I9, and terminals II and I8 are connected by conductors 20 and 2I to terminals 22 and 23 of the starting and running magnetos I0 and II, respectively. The switch I4 is so constructed as to prevent concurrent cirlil cuiting of both magnetos with the spark plug. 1

In Fig. 1 only one terminal on each of the magnetos is shown, it being understood that the electric circuits between the magnetos and spark plug are completed through the provision of a common ground.

Describing now the novel parts of the starting magneto i9 in greater detaiL mounted on the shaft of such magneto is an impulse coupling which includes a hollow circular disc portion 26. An impulse coupling of suitable type, many forms of which are known and now in use, includes a torsion spring (not shown) which is adapted to be manually loaded and released, whereby to impart a rapid rotative impulse to the magneto shaft. In the present instance such actuating spring and attendant elements are installed within the disc portion 24 which forms an operating part of the impulse coupling. When disc 24 is turned through a suitable angular range, say of about 45 degrees, the said actuating spring becomes loaded, the magneto shaft during such movement being locked against rotation. Further or continued turning of the disc 24 results in a tripping or releasing of the means which previously held the magneto shaft against rotation, and the spring reacts to impel the magneto shaft.

The disc 24 is `adapted to be turned or rocked in the recited manner by means of the lever or handle l5 which is rigidly secured to, and projectsY radially from disc 24. In Fig. 3 the broken line showing of handle I5 illustrates that member in its initial or normal position. Rocking movement of handle I5 from its initial position, through a range of approximately 50 degrees in a clockwise direction (Fig. 3) results in consecutive spring loading and latch tripping operations of the impulse coupling as aforesaid, to effect accelerated rotation of the magneto shaft. The full line showing of handle I5, (Fig. 3) 4illustrates that member at its extreme clockwise limit of travel.

The impulse coupling and allied parts are enclosed by a tubular housing or sleeve 26 which is mounted on the circular boss 2'I forming a part of the frame or housing of practically all magnetos of conventional design. Sleeve 26 is slotted longitudinally, and outwardly turned marginal portions extending along the slot provide flanges 28 which receive clamping screws 29, the latter serving to constrict the sleeve and cause the same rigidly to embrace the magneto boss 21. The sleeve 26 is also provided with a circumferential slot 3U through which handle l5 projects, the range of handle movement being limited to the extent of slot 3D.

Projecting axially from the outer face of the disc portion 24 of the impulse coupling is a pin 3| which engages a switch member, to be hereinafter described, and causes such switch member to turn with portion 24 and handle I5. A torsion spring 32, having one end anchored to a stud 33 projecting from the housing 26, and the other end secured to pin 3l, tends to maintain handle l5 in its initial position and to return the handle to such position when displaced therefrom.

The switch assembly includes a disk 34 of insulating material which carries the three circumferentially spaced contact terminals I6, I'I and l. The disc 34 provides a closure for the end of tubular housing 26 and is iixedly secured thereto. Projecting centrally through disc 34 is a shaft 35 which carries a rotatable disc 36 of insulating material, adjacent the inner face of disc 34. Disc 36 is provided with an opening or recess 3'! which receives the end of pin 3l, and by reason of its engagement with pin 3|, disc 36 is caused to rotate conjointly with rotation of handle l5. Embedded in the outer or mating face of disc 36 is a switch blade or conducting strip 38 which is adapted to bridge contacts I6 and il (to place the starting magneto in circuit with the spari; plug), when the disc 36 is rocked clockwise to its extreme position, and to bridge contacts i6 and i 8 (to place the running magneto in circuit with the spark plug) when disc 36 is allowed to` return under the action of spring 32, to its initial or normal position. To assure satisfactory contact between the conducting strip 38 and the contact elements I 6, I'I and I8, a ccmpression spring 39 is mounted on the outwardly projecting end of shaft 35. Such spring exerts an outwardly directed force on the shaft which is transmitted to the rotatable switch disc 36, tending to force the same into pressure engagement with stationary disc 34. The contact elements I 6, I 'I and I3 may consist of screws, the heads of which provide contact surfaces, and the shanks of which pass through to the outer side of disc 34 where they engage terminal sockets 40. The terminal sockets are preferably embedded in insulating bosses 4I which project from the outer face of disc 33.

In Figs. 5 and 6, showing an alternate form of switch construction, the inner face of the stationary disc 34 is provided with a circular recess and disc 36 is journalled for rotation within such recess, no central shaft or pin being used. disc 36 is held in place by the end of the magneto shaft, the housing 26 being adjustably clamped onto the cylindrical boss 2I of the magneto frame and set to provide a minimum running clearance between disc 36 and the end of the magneto shaft.

Describing now the manner in which the described system and means thereof is employed to start a gas or gasoline engine, let it be assumed that the electrical connections as shown in Fig. 1 are provided between the starting and running magnetos, and the spark plug. The operator prepares the engine, first by lling the cylinder with explosive mixture, and next by grasping the flywheel and turning the same backwardly to compress the charge. When maximum compression has been attained, as determined by the physical strength of the operator, he swings the handle I5 from its normal, broken line position (Fig. 3), to the full line position thereof. This movement loads and trips the impulse coupling, and simultaneously switches the spark plug into circuit with the starting magneto, resulting in the production of a spark across the terminals of the spark plug and the firing of the compressed mixture. The operator then allows the handle l5 to be returned by spring 32 to its initial position, causing the starting magneto to be electrically disconnected, and the running or service magneto to be electrically connected to vthe spark plug. The starting magneto is preferably mounted and located on the engine so as to be readily accessible to an operator while he is manipulating the engine fly-wheel.

Having described my invention I claim:

l. In combination with a magneto for providing starting ignition current for an engine having a separate source of running ignition current, animpulse coupling for driving said magneto, a manual lever operatively connected to said impulse coupling, movable in one direction from an initial position to eifect sequential loading and tripping o said impulse coupling, a spring tending to return said lever to its initial position, and a switch operatively connected to said lever, adapted to close the output circuit of said magneto when said lever is disposed in a position to trip said impulse coupling, and to open said circuit when the lever is disposed in its initial position.

2. In. a starting magneto for an internal combustion engine having a source of running ignition current, a magneto rotor shaft, a spring mechanism mounted on the rotor shaft for driving the saine, a handle projecting from the spring mechanism, swingalole from a rst to a second position to effect a driving of the rotor shaft through the action of said spring mechanism, a tubular member extending from the magneto and forming an enclosure for said spring mechanism, ignition circuit connections between the magneto and engine spark plug, a switch mounted on said tubular member and connected in the said circuit, means operatively connecting said switch and handle whereby movement of the handle into its second said position closes the ignition circuit, and a spring associated with said handle tending to return the same to its rst position and to break the ignition circuit.

3. In a magneto adapted to provide starting ignition current for an engine having a source of running ignition current, a rotor, a tubular housing disposed concentrically with the rotor shaft, and projecting from the magneto, a disc of insulating material closing the outer end of said tubular housing, a switch disposed in the output circuit of the magneto, associated with said disc, including contact elements and a switch blade movable to electrically connect and disconnect the contacts, a hand operated spring mechanism mounted on the rotor shaft and enclosed by said tubular housing, a handle projecting from said mechanism through a slot in the housing, said handle being swingable from an initial to a second position whereby to effect a driving of the rotor through the action of said spring mechanism, and means connecting said switch blade for actuation by said handle.

4. In an auxiliary, starting magneto for a gas engine7 a hand operated spring mechanism on one end of the magneto shaft for driving the same, a tubular member extending from the magneto and enclosing said spring mechanism, a switch assembly providing an end closure for said tubular member, including a fixed disc of insulating material having spaced contact elements thereon and a switch blade movable to connect and disconnect the contact elements, said switch being connected in the output circuit of the magneto, a handle operatively associated with said spring mechanism movable forwardly from an initial to a second position to effect a driving of the magneto through the action of the spring mechanism, a spring for returning said handle to its initial position, and means connecting said switch blade for direct actuation by said handle, said switch blade being adapted to interconnect the contact elements when the handle is in its second position, and to disconnect said elements when the handle is in its initial position.

FRANKLIN G. HOBART. 

